Conveyor systems are used for a wide range of purposes. One such purpose is the formatting of one or more streams of product so that, for example, the product spacing corresponds to the spacing needed for a subsequent operation. Such conveyor systems are used, for example, to convert one or two output streams of stacked or shingled meat from a slicing machine into the format required by a packaging machine. Depending on the required format, the conveyor must combine two or more separate streams into a single output stream or multiply the streams into a larger number of output streams. Additionally, the conveyor must properly space the product along both the length and the width of the conveyor to ensure compatibility with the packaging machine.
Conventional conveyor systems for changing the number of streams of product usually include a simple flat belt conveyor and a series of fixed curbs or belt conveyors which guide the products in the lateral direction of the belt conveyor to merge two streams into one or to multiply the number of streams. Examples of these conventional conveying systems are described in FR-A-2587007, FR-A2168967, and U.S. Pat. No. 5,810,149.
U.S. Pat. No. 5,810,149 discloses a conveyor system for accepting one or more streams of product input and converting the one or more streams to a format that is suitable for automatic loading to a subsequent machine. To perform the format conversion some stacks must be temporarily stopped on a moving format conveyor to align lateral rows. The stopping is accomplished by bottom “pop up” stop grids that raise moving stacks from the conveying surface. The A•180® AUTOLOADER™, available from Formax, Inc., of Mokena, Ill., U.S.A. incorporates such stop grids.
While the system described in U.S. Pat. No. 5,810,149 and the A•180® AUTOLOADER™ have achieved success in the formatting of shingled stacks and straight stacks, the present inventors have recognized that frozen, near frozen or otherwise slippery slices of meat or cheese arranged in stacks tend to become disrupted when stopped from force on the bottom slice only by the bottom stop grids.
A typical A•180® AUTOLOADER™ employs the “pop up” stop grids that stop products received from the upstream slicer, in defined rows. The A•180® AUTOLOADER™ can have two or three rows to match packaging machine die formats. The products are typically traveling along the conveyor from 100 to 130 feet per minute when abruptly stopped by the pop up stop grids, triggered by photo eye sensors. Straight stacks of slippery slices tend to at least partially overturn or shuffle due to the inertia of the moving stack and the low coefficient of friction between slices. FIG. 8 illustrates this phenomenon. Stacks that are out of proper alignment can be more difficult to package and can lose an orderly packaged appearance.
The present inventors have recognized the desirability of providing a stack stopping device for a formatting conveyor wherein stacks can be stopped on the conveyor without disturbing stack alignment.
The present inventors have recognized the desirability of providing a product stopping device for a conveyor wherein a quick and complete stop of the product can be ensured.